Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 40
Filter
1.
Mol Cell Biol ; : 1-12, 2024 Jun 03.
Article in English | MEDLINE | ID: mdl-38828991

ABSTRACT

The protein tyrosine phosphatase Src homology region 2 domain-containing phosphatase-1 (SHP-1) plays an important role in modulating glucose and lipid homeostasis. We previously suggested a potential role of SHP-1 in the regulation of peroxisome proliferator-activated receptor γ2 (PPARγ2) expression and activity but the mechanisms were unexplored. PPARγ2 is the master regulator of adipogenesis, but how its activity is regulated by tyrosine phosphorylation is largely unknown. Here, we found that SHP-1 binds to PPARγ2 primarily via its N-terminal SH2-domain. We confirmed the phosphorylation of PPARγ2 on tyrosine-residue 78 (Y78), which was reduced by SHP-1 in vitro resulting in decreased PPARγ2 stability. Loss of SHP-1 led to elevated, agonist-induced expression of the classical PPARγ2 targets FABP4 and CD36, concomitant with increased lipid content in cells expressing PPARγ2, an effect blunted by abrogation of PPARγ2 phosphorylation. Collectively, we discovered that SHP-1 affects the stability of PPARγ2 through dephosphorylation thereby influencing adipogenesis.

2.
J Biol Chem ; 299(9): 105164, 2023 Sep.
Article in English | MEDLINE | ID: mdl-37595871

ABSTRACT

We previously reported that the protein-tyrosine phosphatase SHP-1 (PTPN6) negatively regulates insulin signaling, but its impact on hepatic glucose metabolism and systemic glucose control remains poorly understood. Here, we use co-immunoprecipitation assays, chromatin immunoprecipitation sequencing, in silico methods, and gluconeogenesis assay, and found a new mechanism whereby SHP-1 acts as a coactivator for transcription of the phosphoenolpyruvate carboxykinase 1 (PCK1) gene to increase liver gluconeogenesis. SHP-1 is recruited to the regulatory regions of the PCK1 gene and interacts with RNA polymerase II. The recruitment of SHP-1 to chromatin is dependent on its association with the transcription factor signal transducer and activator of transcription 5 (STAT5). Loss of SHP-1 as well as STAT5 decrease RNA polymerase II recruitment to the PCK1 promoter and consequently PCK1 mRNA levels leading to blunted gluconeogenesis. This work highlights a novel nuclear role of SHP-1 as a key transcriptional regulator of hepatic gluconeogenesis adding a new mechanism to the repertoire of SHP-1 functions in metabolic control.

3.
Arch Gynecol Obstet ; 308(2): 587-597, 2023 08.
Article in English | MEDLINE | ID: mdl-37179499

ABSTRACT

RESEARCH QUESTION: Does complete resection of endometriosis improve embryo quality as assessed by morphokinetic parameters using time-lapse microscopy? DESIGN: For this retrospective study we analysed 237 fertilised, cultured and transferred embryos from 128 fresh IVF and/ or ICSI transfer cycles. Endometriosis was confirmed or excluded by laparoscopy. Patients were stimulated with recombinant FSH using GnRH agonist and antagonist protocols. After fertilisation, a time-lapse incubation system was used for observation. Embryo quality was assessed using the KIDScore™ D3 and D5 implantation data algorithm. RESULTS: The analysis showed a median KIDScore™ D5 of 2.6 (on a scale of 1 to 9.9) for embryos from patients with endometriosis without complete resection. The control group without endometriosis achieved a score of 6.8 (p = 0.003). The median score for embryos from endometriosis patients with complete resection was 7.2, which was a significant increase compared to embryos from patients without complete resection (p = 0.002). We observed an effect size of r = 0.4 for complete resection versus no resection of endometriosis using the KIDScore™ D5. There were no differences in KIDScore™ D3 between the three patient groups. Pregnancy and miscarriage rates showed the same clinical trends. In three of our four case series of patients who underwent IVF/ ICSI cycles before and after complete resection, we found a marked improvement in embryo quality after complete resection. CONCLUSIONS: Complete resection of endometriosis could significantly improve the otherwise poor embryo quality of patients undergoing IVF-procedures. The data, therefore, strongly support recommending surgery to patients with endometriosis prior to assisted reproduction.


Subject(s)
Endometriosis , Pregnancy , Female , Humans , Retrospective Studies , Endometriosis/surgery , Time-Lapse Imaging , Embryonic Development , Algorithms , Fertilization in Vitro , Pregnancy Rate
4.
Int J Mol Sci ; 24(5)2023 Mar 03.
Article in English | MEDLINE | ID: mdl-36902350

ABSTRACT

Developmentally regulated features of innate immunity are thought to place preterm and term infants at risk of infection and inflammation-related morbidity. Underlying mechanisms are incompletely understood. Differences in monocyte function including toll-like receptor (TLR) expression and signaling have been discussed. Some studies point to generally impaired TLR signaling, others to differences in individual pathways. In the present study, we assessed mRNA and protein expression of pro- and anti-inflammatory cytokines in preterm and term cord blood (CB) monocytes compared with adult controls stimulated ex vivo with Pam3CSK4, zymosan, polyinosinic:polycytidylic acid, lipopolysaccharide, flagellin, and CpG oligonucleotide, which activate the TLR1/2, TLR2/6, TLR3, TLR4, TLR5, and TLR9 pathways, respectively. In parallel, frequencies of monocyte subsets, stimulus-driven TLR expression, and phosphorylation of TLR-associated signaling molecules were analyzed. Independent of stimulus, pro-inflammatory responses of term CB monocytes equaled adult controls. The same held true for preterm CB monocytes-except for lower IL-1ß levels. In contrast, CB monocytes released lower amounts of anti-inflammatory IL-10 and IL-1ra, resulting in higher ratios of pro-inflammatory to anti-inflammatory cytokines. Phosphorylation of p65, p38, and ERK1/2 correlated with adult controls. However, stimulated CB samples stood out with higher frequencies of intermediate monocytes (CD14+CD16+). Both pro-inflammatory net effect and expansion of the intermediate subset were most pronounced upon stimulation with Pam3CSK4 (TLR1/2), zymosan (TR2/6), and lipopolysaccharide (TLR4). Our data demonstrate robust pro-inflammatory and yet attenuated anti-inflammatory responses in preterm and term CB monocytes, along with imbalanced cytokine ratios. Intermediate monocytes, a subset ascribed pro-inflammatory features, might participate in this inflammatory state.


Subject(s)
Monocytes , Toll-Like Receptor 4 , Adult , Infant, Newborn , Humans , Monocytes/metabolism , Toll-Like Receptor 4/metabolism , Lipopolysaccharides , Toll-Like Receptor 1/metabolism , Fetal Blood/metabolism , Zymosan , Toll-Like Receptors/metabolism , Cytokines/metabolism , Lipopolysaccharide Receptors/metabolism
5.
J Child Sex Abus ; 32(1): 22-39, 2023 Jan.
Article in English | MEDLINE | ID: mdl-36503514

ABSTRACT

Childhood sexual abuse (CSA) can result in devastating and long lasting consequences. Differences in the nature of the abuse differ for males and females and this difference potentially influences recovery. However, studies of recovery from CSA, especially among men, are relatively few, especially for ethnic minority men. The study explored the lived experience of recovery from CSA among African-Caribbean Black male survivors of CSA living in Canada, the United Kingdom and the United States. The theoretical framework was the transactional model of stress and coping, which proposes that stress is an ongoing transaction between the demands of life and a person's psychological ability to address those demands. The study was qualitative in design, using an interpretive phenomenological approach, involving purposeful sampling, in-depth semi-structured interviews, and interpretive phenomenological analysis of the data informed by a critical race theory lens. The results showed that Black male survivors are situated in unique historical/sociocultural interrelationships that complicate recovery from CSA, including institutional racism and discrimination, restrictive narratives of masculinity, and other cultural norms. These findings can be used to influence policy makers, service providers, and communities, to more effectively support and address the needs of CSA survivors and their affected families.


Subject(s)
Adult Survivors of Child Abuse , Child Abuse, Sexual , Female , Humans , Male , Child , Child Abuse, Sexual/psychology , Ethnicity , Minority Groups , Adaptation, Psychological , Adult Survivors of Child Abuse/psychology
6.
J Neural Transm (Vienna) ; 128(8): 1233-1238, 2021 08.
Article in English | MEDLINE | ID: mdl-34304320

ABSTRACT

Depression is a common psychiatric disorder among geriatric patients that decreases the quality of life and increases morbidity and mortality. Vitamin D as a neuro-steroid hormone might play a role in the onset and treatment of depression. In the present study, the association between depressive symptoms and vitamin D concentration in serum was evaluated. 140 patients of a psychogeriatric day-care unit were included. The geriatric depression scale (GDS) and the Hamilton depression rating scale (HDRS) were assessed at the beginning and end of treatment, GDS scores additionally 6 weeks after discharge from the day-care unit. Vitamin D levels were measured at the beginning of the treatment, routinely. Patients with levels below 30 µg/L were treated with 1000 IU vitamin D per day. There was no association between the severity of depressive symptoms and the concentration of vitamin D at the beginning of the treatment. Patients with higher vitamin D levels showed a stronger decline of depressive symptoms measured by the GDS during their stay in the day-care unit. We provide evidence that vitamin D serum levels might influence antidepressant therapy response in a geriatric population. Prospective studies are necessary to determine which patients may profit from add-on vitamin D therapy.


Subject(s)
Depression , Vitamin D , Aged , Depression/drug therapy , Geriatric Psychiatry , Humans , Prospective Studies , Quality of Life , Self Report
7.
PLoS One ; 16(6): e0253354, 2021.
Article in English | MEDLINE | ID: mdl-34111219

ABSTRACT

[This corrects the article DOI: 10.1371/journal.pone.0217059.].

8.
Front Microbiol ; 12: 691552, 2021.
Article in English | MEDLINE | ID: mdl-34040599

ABSTRACT

[This corrects the article DOI: 10.3389/fmicb.2019.00611.].

9.
Euro Surveill ; 26(1)2021 01.
Article in English | MEDLINE | ID: mdl-33413742

ABSTRACT

Elderly care facilities have become a major focus of coronavirus disease (COVID-19) control. Here, we describe an outbreak of COVID-19 in a nursing home in Germany from 8 March to 4 May 2020 (58 days), and the effect of an intervention of general screening and cohort isolation. COVID-19 cases among residents and staff were recorded on a daily basis from the first positive SARS-CoV-2 test from a resident on 8 March 2020, until 4 May 2020 when the last staff member was classified COVID-19 negative. Eighty of 160 residents (50%) and 37 of 135 staff members (27%) tested positive for SARS-CoV-2. Twenty-seven of the 80 residents were asymptomatic but tested positive during the first general screening. Cohort isolation of SARS-CoV-2 positive residents by reorganising the facility proved to be a major effort. After the intervention, four further asymptomatic residents tested positive in follow-up screenings within a period of 6 days, and were possibly infected prior to the intervention. Thereafter, no further infections were recorded among residents. The described outbreak was controlled by implementing general screening and rigorous cohort isolation, providing a blueprint for similar facilities.


Subject(s)
COVID-19 Testing , COVID-19/prevention & control , Disease Outbreaks/prevention & control , Homes for the Aged , Nursing Homes , Quarantine , Aged , Aged, 80 and over , COVID-19/diagnosis , COVID-19/epidemiology , Female , Follow-Up Studies , Germany/epidemiology , Humans , Male , Outcome and Process Assessment, Health Care , Retrospective Studies
10.
Gynecol Obstet Invest ; 85(5): 428-436, 2020.
Article in English | MEDLINE | ID: mdl-33171480

ABSTRACT

INTRODUCTION: Expression of fibroblast activation protein (FAP) has been detected in activated fibroblasts participating in injury response, fibrotic and inflammatory conditions, and tumorigenesis. Human endometrium is equally characterized by rapid tissue remodeling events due to the reproductive tasks comprising the activity of proteolytic enzymes. OBJECTIVE: We therefore hypothesized that FAP-positive fibroblasts could also be involved in physiological processes requiring tissue remodeling, such as decidualization during early pregnancy. METHODS/RESULTS: The expression of FAP was analyzed by immunohistochemistry in frozen sections of decidual tissue from early pregnancy (gestational weeks: 6-12). All tissue samples clearly displayed a strong expression of FAP on the surface of stromal fibroblasts. Additionally, the percentage of FAP-positive fibroblasts freshly isolated from the decidua of the corresponding gestational weeks was calculated by applying FACS analysis. Decidual fibroblasts of different gestational weeks showed a significant decrease in FAP expression between the 6th and 7th weeks of gestation, which was followed by a steady slow reconstitution. By analyzing the expression of cytokines, chemokines, and growth factors of isolated FAP-positive decidual fibroblasts, we detected high levels of monocyte-attracting chemokines (growth-related oncogene alpha and monocyte chemoattractant protein-1 and -2), granulocyte-attracting chemokines (e.g., IL-8), proinflammatory factors (IL-1α and tumor necrosis factor alpha), and angiogenic substances (e.g., vascular endothelial growth factor and IL-8), which all promote an optimal microenvironment for implantation and growth of the conceptus. CONCLUSIONS: Our data demonstrate that the healthy early pregnancy decidua is characterized by a general occurrence of FAP-positive fibroblasts possibly participating in active tissue remodeling during implantation.


Subject(s)
Chemokines/metabolism , Decidua/metabolism , Fibroblasts/metabolism , Gelatinases/metabolism , Membrane Proteins/metabolism , Pregnancy/metabolism , Serine Endopeptidases/metabolism , Chemokine CCL2/metabolism , Chemokine CCL8/metabolism , Chemokine CXCL1/metabolism , Decidua/cytology , Endopeptidases , Female , Fibroblasts/physiology , Gestational Age , Humans , Immunohistochemistry , Interleukin-1alpha/metabolism , Interleukin-8/metabolism , Stromal Cells/metabolism , Tumor Necrosis Factor-alpha/metabolism , Vascular Endothelial Growth Factor A/metabolism
11.
Mol Metab ; 42: 101067, 2020 12.
Article in English | MEDLINE | ID: mdl-32860984

ABSTRACT

OBJECTIVE: Hyperinsulinemia can be both a cause and consequence of obesity and insulin resistance. Hyperinsulinemia can result from increased insulin secretion and/or reduced insulin clearance. While many studies have focused on mechanisms triggering insulin secretion during obesity, the triggers for changes in insulin clearance during obesity are less defined. In this study, we investigated the role of the microbiota in regulating insulin clearance during diet-induced obesity. METHODS: Blood glucose and insulin clearance were tested in conventional male mice treated with antibiotics and germ-free mice colonized with microbes from mice that were fed a control (chow) diet or an obesogenic high-fat diet (HFD). The composition of the fecal microbiota was analyzed using 16S rRNA sequencing. RESULTS: Short-term HFD feeding and aging did not alter insulin clearance in the mice. Oral antibiotics mitigated impaired blood insulin clearance in the mice fed an HFD for 12 weeks or longer. Germ-free mice colonized with microbes from HFD-fed donor mice had impaired insulin but not C-peptide clearance. Microbe-transmissible insulin clearance impairment was only observed in germ-free mice after more than 6 weeks post-colonization upon HFD feeding. Five bacterial taxa predicted >90% of the variance in insulin clearance. Mechanistically, impaired insulin clearance was associated with lower levels of hepatic Ceacam-1 but increased liver and skeletal muscle insulin-degrading enzyme (IDE) activity. CONCLUSIONS: Gut microbes regulate insulin clearance during diet-induced obesity. A small cluster of microbes or their metabolites may be targeted for mitigating defects in insulin clearance and hyperinsulinemia during the progression of obesity and type 2 diabetes.


Subject(s)
Gastrointestinal Microbiome/physiology , Insulin/metabolism , Obesity/microbiology , Animals , Blood Glucose/metabolism , Diet, High-Fat , Feces/microbiology , Glucose/metabolism , Hyperinsulinism/metabolism , Insulin Resistance/physiology , Liver/metabolism , Male , Mice , Mice, Inbred C57BL , Mice, Obese , Obesity/metabolism , RNA, Ribosomal, 16S
12.
BMC Neurol ; 20(1): 276, 2020 Jul 11.
Article in English | MEDLINE | ID: mdl-32652957

ABSTRACT

BACKGROUND: There is growing evidence for proprioceptive dysfunction in patients with Parkinson's disease (PD). The Lee Silvermann Voice Treatment-BIG therapy (LSVT-BIG), a special training program aiming at an increase of movement amplitudes in persons with PD (PwPD), has shown to be effective on motor symptoms. LSVT-BIG is conceptionally based on improving bradykinesia, in particular the decrement of repetitive movements, by proprioceptive recalibration. OBJECTIVE: To assess proprioceptive impairment in PwPD as compared to matched controls and to probe potential recalibration effects of the LSVT-BIG therapy on proprioception. METHODS: Proprioceptive performance and fine motor skills were assessed in 30 PwPD and 15 matched controls. Measurements with significant impairment in PwPD were chosen as outcome parameters for a standardized 4 weeks amplitude-based training intervention (LSVT-BIG) in 11 PwPD. Proprioceptive performance served as primary outcome measure. Secondary outcome measures included the motor part of the MDS-UPDRS, the nine-hole-peg test, and a questionnaire on quality of life. Post-interventional assessments were conducted at weeks 4 and 8. RESULTS: Compared to the control group, PwPD showed significantly larger pointing errors. After 4 weeks of LSVT-BIG therapy and even more so after an additional 4 weeks of continued training, proprioceptive performance improved significantly. In addition, quality of life improved as indicated by a questionnaire. CONCLUSION: LSVT-BIG training may achieve a recalibration of proprioceptive processing in PwPD. Our data indicates a probable physiological mechanism of a symptom-specific, amplitude-based behavioral intervention in PwPD.


Subject(s)
Exercise Therapy , Parkinson Disease/therapy , Proprioception/physiology , Aged , Female , Humans , Male , Middle Aged , Quality of Life
13.
PLoS One ; 14(5): e0217059, 2019.
Article in English | MEDLINE | ID: mdl-31095643

ABSTRACT

Microbial colonization can be detrimental to the integrity of metal surfaces and lead to microbiologically influenced corrosion (MIC). Biocorrosion is a serious problem for aquatic and marine industries in the world. In Minnesota (USA), where this study was conducted, biocorrosion severely affects the maritime transportation industry. The anticorrosion activity of a variety of compounds, including chemical (magnesium peroxide) and biological (surfactin, capsaicin, and gramicidin) molecules were investigated as coating additives. We also evaluated a previously engineered, extremely stable, non-biocidal enzyme known to interfere in bacterial signaling, SsoPox (a quorum quenching lactonase). Experimental steel coupons were submerged in water from the Duluth Superior Harbor (DSH) for 8 weeks in the laboratory. Biocorrosion was evaluated by counting the number and the coverage of corrosion tubercles on coupons and also by ESEM imaging of the coupon surface. Three experimental coating additives significantly reduced the formation of corrosion tubercles: surfactin, magnesium peroxide and the quorum quenching lactonase by 31%, 36% and 50%, respectively. DNA sequence analysis of the V4 region of the bacterial 16S rRNA gene revealed that these decreases in corrosion were associated with significant changes in the composition of bacterial communities on the steel surfaces. These results demonstrate the potential of highly stable quorum quenching lactonases to provide a reliable, cost-effective method to treat steel structures and prevent biocorrosion.


Subject(s)
Bacteria/drug effects , Quorum Sensing , Steel/chemistry , Anti-Bacterial Agents/chemistry , Biofilms/drug effects , Capsaicin/chemistry , Carboxylic Ester Hydrolases/chemistry , Corrosion , Gramicidin/chemistry , Lipopeptides/chemistry , Magnesium Compounds/chemistry , Minnesota , Peptides, Cyclic/chemistry , Peroxides/chemistry , RNA, Ribosomal, 16S/metabolism , Surface Properties , Water Microbiology
14.
Front Microbiol ; 10: 611, 2019.
Article in English | MEDLINE | ID: mdl-30984139

ABSTRACT

The disruption of bacterial signaling (quorum quenching) has been proven to be an innovative approach to influence the behavior of bacteria. In particular, lactonase enzymes that are capable of hydrolyzing the N-acyl homoserine lactone (AHL) molecules used by numerous bacteria, were reported to inhibit biofilm formation, including those of freshwater microbial communities. However, insights and tools are currently lacking to characterize, understand and explain the effects of signal disruption on complex microbial communities. Here, we produced silica capsules containing an engineered lactonase that exhibits quorum quenching activity. Capsules were used to design a filtration cartridge to selectively degrade AHLs from a recirculating bioreactor. The growth of a complex microbial community in the bioreactor, in the presence or absence of lactonase, was monitored over a 3-week period. Dynamic population analysis revealed that signal disruption using a quorum quenching lactonase can effectively reduce biofilm formation in the recirculating bioreactor system and that biofilm inhibition is concomitant to drastic changes in the composition, diversity and abundance of soil bacterial communities within these biofilms. Effects of the quorum quenching lactonase on the suspension community also affected the microbial composition, suggesting that effects of signal disruption are not limited to biofilm populations. This unexpected finding is evidence for the importance of signaling in the competition between bacteria within communities. This study provides foundational tools and data for the investigation of the importance of AHL-based signaling in the context of complex microbial communities.

15.
Chembiochem ; 20(14): 1848-1855, 2019 07 15.
Article in English | MEDLINE | ID: mdl-30864300

ABSTRACT

Quorum quenching lactonases are enzymes capable of hydrolyzing lactones, including N-acyl homoserine lactones (AHLs). AHLs are molecules known as signals in bacterial communication dubbed quorum sensing. Bacterial signal disruption by lactonases was previously reported to inhibit behavior regulated by quorum sensing, such as the expression of virulence factors and the formation of biofilms. Herein, we report the enzymatic and structural characterization of a novel lactonase representative from the metallo-ß-lactamase superfamily, dubbed GcL. GcL is a broad spectrum and highly proficient lactonase, with kcat /KM values in the range of 104 to 106 m-1 s-1 . Analysis of free GcL structures and in complex with AHL substrates of different acyl chain length, namely, C4-AHL and 3-oxo-C12-AHL, allowed their respective binding modes to be elucidated. Structures reveal three subsites in the binding crevice: 1) the small subsite where chemistry is performed on the lactone ring; 2) a hydrophobic ring that accommodates the amide group of AHLs and small acyl chains; and 3) the outer, hydrophilic subsite that extends to the protein surface. Unexpectedly, the absence of structural accommodation for long substrate acyl chains seems to relate to the broad substrate specificity of the enzyme.


Subject(s)
Acyl-Butyrolactones/chemistry , Bacterial Proteins/chemistry , Carboxylic Ester Hydrolases/chemistry , Acyl-Butyrolactones/metabolism , Bacillaceae/enzymology , Bacterial Proteins/metabolism , Carboxylic Ester Hydrolases/metabolism , Catalytic Domain , Hydrophobic and Hydrophilic Interactions , Protein Binding , Substrate Specificity
16.
Geburtshilfe Frauenheilkd ; 79(3): 281-285, 2019 Mar.
Article in English | MEDLINE | ID: mdl-30880826

ABSTRACT

FATWO (female adnexal tumour of probable Wolffian origin) denotes a rare tumour of the female adnexa which has been described in nearly 80 cases worldwide and which presumably originates in the remains of the Wolffian ducts. In 10 to 20 percent of patients, a metastasis or recurrence was seen subsequently and for this reason, a malignant potential is attributed to the FATWO. Because of the small number of cases, there is no clear therapeutic recommendation. The method of choice currently is surgical treatment with hysterectomy and adnexectomy. The benefit of radio- and chemotherapies is not clear and a small number of treatment attempts with imatinib have been made in cases of CD117 positivity or treatment attempts on an endocrine basis. This work provides an overview of the literature on epidemiology, imaging and histopathological diagnostic features as well as therapeutic options of this same tumour form.

17.
Sci Rep ; 8(1): 11262, 2018 07 26.
Article in English | MEDLINE | ID: mdl-30050039

ABSTRACT

Quorum quenching lactonases are enzymes that are capable of disrupting bacterial signaling based on acyl homoserine lactones (AHL) via their enzymatic degradation. In particular, lactonases have therefore been demonstrated to inhibit bacterial behaviors that depend on these chemicals, such as the formation of biofilms or the expression of virulence factors. Here we characterized biochemically and structurally a novel representative from the metallo-ß-lactamase superfamily, named AaL that was isolated from the thermoacidophilic bacterium Alicyclobacillus acidoterrestris. AaL is a potent quorum quenching enzyme as demonstrated by its ability to inhibit the biofilm formation of Acinetobacter baumannii. Kinetic studies demonstrate that AaL is both a proficient and a broad spectrum enzyme, being capable of hydrolyzing a wide range of lactones with high rates (kcat/KM > 105 M-1.s-1). Additionally, AaL exhibits unusually low KM values, ranging from 10 to 80 µM. Analysis of AaL structures bound to phosphate, glycerol, and C6-AHL reveals a unique hydrophobic patch (W26, F87 and I237), involved in substrate binding, possibly accounting for the enzyme's high specificity. Identifying the specificity determinants will aid the development of highly specific quorum quenching enzymes as potential therapeutics.


Subject(s)
Alicyclobacillus/enzymology , Hydrolases/chemistry , Hydrolases/metabolism , Lactones/metabolism , Acinetobacter baumannii/drug effects , Acinetobacter baumannii/growth & development , Binding Sites , Biofilms/drug effects , Biofilms/growth & development , Crystallography, X-Ray , Hydrolases/isolation & purification , Hydrolysis , Kinetics , Models, Molecular , Protein Binding , Protein Conformation , Quorum Sensing , Substrate Specificity
18.
Acta Crystallogr F Struct Biol Commun ; 73(Pt 8): 476-480, 2017 Aug 01.
Article in English | MEDLINE | ID: mdl-28777091

ABSTRACT

Lactonases comprise a class of enzymes that hydrolyze lactones, including acyl-homoserine lactones (AHLs); the latter are used as chemical signaling molecules by numerous Gram-negative bacteria. Lactonases have therefore been demonstrated to quench AHL-based bacterial communication. In particular, lactonases are capable of inhibiting bacterial behaviors that depend on these chemicals, such as the formation of biofilms or the expression of virulence factors. A novel representative from the metallo-ß-lactamase superfamily, named AaL, was isolated from the thermoacidophilic bacterium Alicyclobacter acidoterrestris. Kinetic characterization proves AaL to be a proficient lactonase, with catalytic efficiencies (kcat/Km) against AHLs in the region of 105 M-1 s-1. AaL exhibits a very broad substrate specificity. Its structure is expected to reveal the molecular determinants for its substrate binding and specificity, as well as to provide grounds for future protein-engineering projects. Here, the expression, purification, characterization, crystallization and X-ray diffraction data collection of AaL at 1.65 Šresolution are reported.


Subject(s)
Bacterial Proteins/chemistry , Carboxylic Ester Hydrolases/chemistry , Firmicutes/chemistry , Quorum Sensing/genetics , Amino Acid Sequence , Bacterial Proteins/genetics , Bacterial Proteins/metabolism , Carboxylic Ester Hydrolases/genetics , Carboxylic Ester Hydrolases/metabolism , Cloning, Molecular , Crystallization , Crystallography, X-Ray , Escherichia coli/genetics , Escherichia coli/metabolism , Firmicutes/metabolism , Gene Expression , Genetic Vectors/chemistry , Genetic Vectors/metabolism , Kinetics , Recombinant Proteins/chemistry , Recombinant Proteins/genetics , Recombinant Proteins/metabolism
19.
J Cell Biochem ; 118(5): 1216-1226, 2017 05.
Article in English | MEDLINE | ID: mdl-27791266

ABSTRACT

It is known that interfering with glycolysis leads to profound modification of cancer cell proliferation. However, energy production is not the major reason for this correlation. Here, using HeLa cells as a model for cancer, we demonstrate that phosphofructokinase-P (PFK-P), which is overexpressed in diverse types of cancer including HeLa cells, modulates expression of P44/42 mitogen-activated protein kinase (MAPK). Silencing of PFK-P did not alter HeLa cell viability or energy production, including the glycolytic rate. On the other hand, silencing of PFK-P induced the downregulation of p44/42 MAPK, augmenting the sensitivity of HeLa cells to different drugs. Conversely, overexpression of PFK-P promotes the upregulation of p44/42 MAPK, making the cells more resistant to the drugs. These results indicate that overexpression of PFK-P by cancer cells is related to activation of survival pathways via upregulation of MAPK and suggest PFK-P as a promising target for cancer therapy. J. Cell. Biochem. 118: 1216-1226, 2017. © 2016 Wiley Periodicals, Inc.


Subject(s)
Mitogen-Activated Protein Kinase 1/metabolism , Mitogen-Activated Protein Kinase 3/metabolism , Phosphofructokinase-1/genetics , Phosphofructokinase-1/metabolism , Cell Proliferation , Cell Survival , Gene Silencing , Glycolysis , HeLa Cells , Humans , Signal Transduction
20.
Acta Crystallogr F Struct Biol Commun ; 72(Pt 9): 681-6, 2016 09.
Article in English | MEDLINE | ID: mdl-27599858

ABSTRACT

Lactonases are enzymes that are capable of hydrolyzing various lactones such as aliphatic lactones or acyl-homoserine lactones (AHLs), with the latter being used as chemical signaling molecules by numerous Gram-negative bacteria. Lactonases therefore have the ability to quench the chemical communication, also known as quorum sensing, of numerous bacteria, and in particular to inhibit behaviors that are regulated by this system, such as the expression of virulence factors or the production of biofilms. A novel representative from the metallo-ß-lactamase superfamily, dubbed GcL, was isolated from the thermophilic bacterium Geobacillus caldoxylosilyticus. Because of its thermophilic origin, GcL may constitute an interesting candidate for the development of biocontrol agents. Here, we show that GcL is a thermostable enzyme with a half-life at 75°C of 152.5 ± 10 min. Remarkably, it is also shown that GcL is among the most active lactonases characterized to date, with catalytic efficiencies (kcat/Km) against AHLs of greater than 10(6) M(-1) s(-1). The structure of GcL is expected to shed light on the catalytic mechanism of the enzyme and the molecular determinants for the substrate specificity in this class of lactonases. Here, the expression, purification, characterization, crystallization and X-ray diffraction data collection to 1.6 Šresolution of GcL are reported.


Subject(s)
Acyl-Butyrolactones/chemistry , Bacterial Proteins/chemistry , Carboxylic Ester Hydrolases/chemistry , Geobacillus/chemistry , Quorum Sensing , Acyl-Butyrolactones/metabolism , Amino Acid Sequence , Bacterial Proteins/genetics , Bacterial Proteins/metabolism , Biocatalysis , Carboxylic Ester Hydrolases/genetics , Carboxylic Ester Hydrolases/metabolism , Cloning, Molecular , Crystallization , Crystallography, X-Ray , Enzyme Stability , Escherichia coli/genetics , Escherichia coli/metabolism , Gene Expression , Geobacillus/enzymology , Hot Temperature , Hydrolysis , Kinetics , Plasmids/chemistry , Plasmids/metabolism , Recombinant Proteins/chemistry , Recombinant Proteins/genetics , Recombinant Proteins/metabolism , X-Ray Diffraction
SELECTION OF CITATIONS
SEARCH DETAIL
...